No abstract

This paper discusses how network theory and social capital can help explain different patterns of inclusion of small and medium sized producers in agri-food clusters. We make the argument that despite the centralized nature of practices, the manner in which inclusion takes place can vary significantly depending on structural features of local networks and governance factors, especially social capital and the role of lead organisations. Social network analysis allows us to investigate how different patterns of bonding, bridging and centrality of key actors in agricultural clusters can influence diffusion of knowledge. We frame this discussion through a typology that allows us to identify diverse scenarios of inclusion of small producers. This is then used to guide an empirical analysis of two agri-food clusters of small producers in Peru (mango) and Colombia (palm oil). Judicious use of mixed methods and the typology can prove useful to explain diverse patterns of inclusion which have important implications for small-scale agricultural producers.

Various cellulose‐2,3‐bis‐arylcarbamate‐6‐O‐arylesters and cellulose‐2,3‐bis‐arylester‐6‐O‐arylcarbamates, designed to test the possible combined effects of the known tris‐arylcarbamate and tris‐arylester classes, were synthesized with high regioselectivity at O‐C(6), and their use as CSPs in liquid chromatography for enantiomeric separations was investigated. The separations obtained with the synthesized CSPs were compared to the separations achieved on a self‐packed reference column, consisting of cellulose‐tris‐(3,5‐dimethylphenyl‐carbamate) as CSP standard. Among the synthesized, regioselectively substituted cellulose derivatives, 2,3‐bis‐O‐(3,5‐dimethylphenylcarbamate)‐6‐O‐benzoate‐cellulose and 2,3‐bis‐O‐(benzoate)‐6‐O‐(3,5‐dichlorophenylcarbamate)‐cellulose gave the best CSPs for the separation of the test racemates. CSPs from regioselectively substituted cellulose derivatives seem to exhibit higher selectivities than cellulose‐tris‐(3,5‐dimethylphenylcarbamate) for certain classes of racemic compounds. Chirality 10:294–306, 1998. © 1998 Wiley‐Liss, Inc.

Alterations in the 5-HT2A receptor gene expression in the prefrontal cortex have been suggested to play a role in the pathophysiology and pharmacotherapy of schizophrenia. This study measured mRNA encoding 5-HT2A receptor in the left superior frontal gyrus from chronic elderly schizophrenics (n = 21) with varying neuroleptic-free intervals before death (72 hr to more than 5 years), and normal drug-free elderly controls (n = 14). Levels of 5-HT2A mRNA in schizophrenics correlated significantly and inversely with neuroleptic-free interval before death (r = -0.77; P < 0.0001). In schizophrenics who had been receiving neuroleptic until time of death, levels of 5-HT2A mRNA were similar to controls or greater. In schizophrenics who had been free of neuroleptic for more than six months levels of 5-HT2A mRNA were significantly lower than in controls. These results confirm previous findings of decreased expression of the 5-HT2A receptor gene in the frontal cortex of some schizophrenics and suggest that regulation of this gene may be involved in the therapeutic actions of typical neuroleptics.

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